Preheat oven to 350 degrees.
In a mixing bowl, cream the sugar and oil, beating until light and fluffy. Add the eggs, one at a time, and mix well after each addition. Mix the cocoa and food coloring together then add to sugar mixture; mix well. Sift together the flour and slat; add to the creamed mixture alternately with the buttermilk. Blend in vanilla. In a small bowl combine the baking soda and vinegar; add to mixture. Pour batter into three greased 8-inch round cake pans and bake for 20-25 minutes or until a toothpick inserted into the center of each cake comes out clean. Remove from oven and cool completely before frosting.
For the icing, blend the cream cheese and butter together in a mixing bowl. Add the sugar and continue to blend. Fold in the nuts. Spread between layers and on top and sides of cooled cake.

(This recipe was contributed as part of a "Cook of the Week" feature.)